U.S. patent application number 10/335975 was filed with the patent office on 2004-07-08 for multi-pressure regulating valve system for expander.
Invention is credited to Jackson, Stephen.
Application Number | 20040129431 10/335975 |
Document ID | / |
Family ID | 32680896 |
Filed Date | 2004-07-08 |
United States Patent
Application |
20040129431 |
Kind Code |
A1 |
Jackson, Stephen |
July 8, 2004 |
Multi-pressure regulating valve system for expander
Abstract
The present invention provides a method and apparatus for
regulating pressure within a closed expansion system. In one aspect
of the invention, the apparatus comprises an expander tool
comprising a first pressure regulation system disposed within an
expansion chamber. The first pressure regulation system comprises
two valves which regulate pressure within the expansion system
during run-in. In another aspect of the invention, the apparatus
comprises an expander tool comprising an expansion chamber in fluid
communication with a second pressure regulation system. The second
pressure regulation system regulates pressure during the expansion
of a tubular. The second pressure regulation system comprises a
frangible member and a valve in series, and optionally a pressure
regulator downstream of the frangible member and valve in series.
In another aspect of the invention, a method is provided for
regulating pressure during the expansion process using the first
and/or second pressure regulation system.
Inventors: |
Jackson, Stephen; (Richmond,
TX) |
Correspondence
Address: |
MOSER, PATTERSON & SHERIDAN, L.L.P.
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056-6582
US
|
Family ID: |
32680896 |
Appl. No.: |
10/335975 |
Filed: |
January 2, 2003 |
Current U.S.
Class: |
166/384 ;
166/207 |
Current CPC
Class: |
E21B 43/105
20130101 |
Class at
Publication: |
166/384 ;
166/207 |
International
Class: |
E21B 023/02 |
Claims
1. A method for expanding a tubular within a wellbore, comprising:
attaching an expander tool to the lower end of a working string,
the expander tool comprising an expansion chamber in fluid
communication with a frangible member in series with a valve;
running the working string with the expander tool into the
wellbore; expanding the tubular at a first pressure into
substantial contact with a casing wall of the wellbore; and
expanding the tubular at a second pressure.
2. The method of claim 1, wherein the first pressure is higher than
the second pressure.
3. The method of claim 1, wherein the frangible member breaks
before expanding the tubular at a second pressure.
4. The method of claim 3, wherein the valve operates after the
frangible member breaks.
5. The method of claim 1, wherein the frangible member is a burst
plug.
6. The method of claim 1, wherein the valve is a check valve.
7. The method of claim 1, wherein the expander tool further
comprises a regulator valve in fluid communication with the
expansion chamber.
8. The method of claim 7, wherein the regulator valve creates a
back pressure on the frangible member in series with the valve,
thereby increasing response time of the valve.
9. The method of claim 1, wherein the expander tool further
comprises at least two valves which regulate differential pressure
between the expansion chamber of the expander tool and an exterior
of the expander tool while running the working string with the
expander tool into the wellbore.
10. The method of claim 9, wherein the at least two valves comprise
a first valve which allows fluid to flow into the exterior of the
expander tool.
11. The method of claim 10, wherein the at least two valves further
comprise a second valve which allows fluid to flow into the
expansion chamber.
12. The method of claim 9, further comprising the step of
substantially obstructing flow through the at least two valves
before the step of expanding the tubular at a first pressure into
substantial contact with a casing wall.
13. The method of claim 12, wherein the substantially obstructing
flow through at least two valves further comprises plugging
openings of the at least two valves.
14. An expander tool for expanding a tubular body, the expander
tool comprising: an expansion chamber; and a frangible member in
series with a valve in fluid communication with the expansion
chamber.
15. The expander tool of claim 14, further comprising a regulator
valve in fluid communication with the expansion chamber.
16. The expander tool of claim 15, wherein the regulator valve is
located downstream of the frangible member in series with the
valve.
17. The expander tool of claim 14, wherein the frangible member
bursts upon constraint of the expander tool.
18. The expander tool of claim 14, wherein the frangible member is
a burst plug.
19. The expander tool of claim 14, wherein the valve regulates
fluid flow at a reduced rate after the frangible member bursts upon
constraint.
20. The expander tool of claim 15, wherein the regulator valve
operates through a jetting action of a tortuous path of fluid.
21. The expander tool of claim 15, wherein the regulator valve
creates a back pressure on the frangible member in series with the
valve.
22. The expander tool of claim 15, wherein the regulator valve is a
jetted valve.
23. The expander tool of claim 14, further comprising at least two
valves disposed inside the expansion chamber.
24. The expander tool of claim 23, wherein the at least two valves
regulate differential pressure between the expansion chamber and an
outside of the expander tool.
25. The expander tool of claim 24, wherein the at least two valves
comprise a first valve which permits pressure from the expansion
chamber to release into the outside of the expander tool.
26. The expander tool of claim 25, wherein the at least two valves
further comprise a second valve which permits pressure from the
outside of the expander tool to release into the expansion
chamber.
27. An expander tool comprising: means for expanding a tubular at a
first pressure until the tubular contacts a casing wall of a
wellbore; and means for expanding a tubular at a second pressure
after the tubular contacts the casing wall of the wellbore.
28. The expander tool of claim 27, wherein the first pressure is
higher than the second pressure.
29. The expander tool of claim 28, further comprising means for
regulating the transition between the means for expanding the
tubular at the first pressure and the means for expanding the
tubular at a second pressure.
30. The expander tool of claim 27, further comprising means for
decreasing differential pressure between an inside portion of the
expander tool and an outside portion of the expander tool.
31. A method for expanding a tubular within a wellbore, comprising:
running a working string into the wellbore with an expander tool
attached to the lower end, the expander tool comprising: an
expansion chamber in fluid communication with a frangible member in
series with a check valve; and at least two valves; regulating
differential pressure between the expansion chamber and an exterior
of the expander tool with the at least two valves while running the
working string into the wellbore; expanding the tubular at a first
pressure into substantial contact with a casing wall of the
wellbore; allowing sufficient pressure to break the frangible
member to accumulate within the expansion chamber; and expanding
the tubular at a second pressure.
32. An expander tool for expanding a tubular body within a
wellbore, the expander tool comprising: an expansion chamber
comprising two valves which regulate differential pressure between
an inside of the expansion chamber and an outside of the expansion
chamber; and a frangible member in series with a valve in fluid
communication with the inside of the expansion chamber.
33. The expander tool of claim 32, further comprising a regulator
valve located downstream of the frangible member, wherein the
regulator valve is in fluid communication with the expansion
chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to wellbore completion. More
particularly, the invention relates to an expansion system for
expanding strings of casing within a wellbore. More particularly
still, the invention relates to an apparatus and method for
regulating expansion force in an expander tool for expanding a
tubular body. More particularly still, the apparatus relates to a
valve system for regulating pressure within an expansion chamber
during expansion of the strings of casing as well as during run-in
of the expansion system into the wellbore.
[0003] 2. Description of the Related Art
[0004] Hydrocarbon and other wells are completed by forming a
borehole in the earth and then lining the borehole with steel pipe
or casing to form a wellbore. After a section of wellbore is formed
by drilling, a string of casing is lowered into the wellbore and
temporarily hung therein from the surface of the well. Using
apparatus known in the art, the casing is cemented into the
wellbore by circulating cement into the annular area defined
between the outer wall of the casing and the borehole. The
combination of cement and casing strengthens the wellbore and
facilitates the isolation of certain areas of the formation behind
the casing for the production of hydrocarbons.
[0005] It is common to employ more than one string of casing in a
wellbore. In this respect, a first string of casing is set in the
wellbore when the well is drilled to a first designated depth. The
first string of casing is hung from the surface, and then cement is
circulated into the annulus behind the casing. The well is then
drilled to a second designated depth, and a second string of
casing, or liner, is run into the well. The second string is set at
a depth such that the upper portion of the second string of casing
overlaps the lower portion of the first string of casing. The
second liner string is then fixed or "hung" off of the existing
casing by the use of slips which utilize slip members and cones to
wedgingly fix the new string of liner in the wellbore. The second
casing string is then cemented. This process is typically repeated
with additional casing strings until the well has been drilled to
total depth. In this manner, wells are typically formed with two or
more strings of casing of an ever decreasing diameter.
[0006] Apparatus and methods exist that permit tubulars to be
expanded within a wellbore. The apparatus typically includes
expander tools which are fluid powered and are run into the
wellbore on a working string. The hydraulic expander tools include
radially expandable members which, through fluid pressure, are
urged outward radially from the body of the expander tool and into
contact with a tubular therearound. As sufficient pressure is
generated on a piston surface behind these expansion members, the
tubular being acted upon by the expansion tool is expanded past its
point of elastic deformation. In this manner, the inner and outer
diameters of the tubular are increased in the wellbore. By rotating
the expander tool in the wellbore and/or moving the expander tool
axially in the wellbore with the expansion member actuated, a
tubular can be expanded into plastic deformation along a
predetermined length in a wellbore.
[0007] A known apparatus used to expand tubulars in a wellbore is a
closed system expander tool. A closed system expander tool
comprises an expansion chamber which contains hydraulic fluid. The
hydraulic fluid is inserted into the expansion chamber before the
expander tool is run into the wellbore. In this way, it is not
necessary to introduce hydraulic fluid into the wellbore from the
surface after the expander tool is run into the wellbore to actuate
the expander tool. Rather, fluid pressure from within the expansion
chamber activates the expander tool.
[0008] Multiple uses for expandable tubulars are being discovered.
For example, an intermediate string of casing can be hung off of a
string of surface casing by expanding an upper portion of the
intermediate string into frictional contact with the lower portion
of surface casing therearound. This allows for the hanging of a
string of casing without the need for a separate slip assembly as
described above. Additional applications for the expansion of
downhole tubulars exist. These include the use of an expandable
sand screen, employment of an expandable seat for seating a
diverter tool, and the use of an expandable seat for setting a
packer.
[0009] One problem with existing closed expansion systems is the
risk of collapse of the expander tool due to differential pressures
between the inside and the outside of the expansion chamber as the
expander tool is run into the wellbore. When the expansion system
is operated as a closed system, a difference in pressure develops
between the annular area which is between the outer diameter of the
expander tool and the inner diameter of the casing string to be
expanded, and the expansion chamber of the closed expansion system.
The difference in pressure between the two areas can result from
air pockets trapped in the closed system or from thermal expansion
of fluid in the closed system. Trapped air pockets in the closed
expansion system cause the pressure of the annular space to become
higher than the pressure of the closed expansion system, as the
trapped air in the expansion system creates a pressure drop within
the expansion system relative to the annular space. This pressure
differential causes stress upon the outside of the expansion
chamber. In contrast, thermal expansion of fluid within the
expansion system causes the pressure of the closed expansion system
to become higher than the pressure in the annular space. Often, the
temperature within the wellbore is much higher than the temperature
at the surface. The hydraulic fluid within the expansion chamber
may expand in volume due to the heat as the expander tool is run
into the wellbore, thus creating a stress on the inside of the
expansion chamber. The pressure differential created either by
trapped air pockets or thermal expansion of fluid in the closed
system increases the risk of collapse of the expansion system
during run-in.
[0010] An additional problem with the prior art expansion systems
occurs during the expansion process itself. The expansion process
begins after the expander tool is lowered to a desired depth within
the wellbore. The expander tool is rotated and pressure is exerted
onto the tubular to be expanded by the expander tool, causing the
tubular material to expand radially. The expander tool initially
expands the tubular radially outward through the annular space.
Next, the tubular being expanded hits the constraint point, which
is typically the inner diameter of the well casing within the
wellbore. After hitting the constraint point, the expander tool is
moved axially as well as radially so that the tubular is expanded
throughout the length of the tubular.
[0011] Greater pressure is required to initiate expansion than to
maintain expansion after hitting the constraint point. Therefore,
more pressure is necessary at the beginning of the expansion
process than is necessary to maintain expansion along the length of
the tubular being expanded. Existing expansion systems allow
pressure exertion on the tubular at the same rate throughout the
expansion process. Expansion at the same rate throughout the
process over-expands the tubular after the tubular hits the
constraint point, creating excessive thinning of the tubular wall
when the expander tool is allowed to expand the length of the
tubular while rotating and moving axially.
[0012] Therefore, a need exists for a pressure regulation system
for an expander tool which effectively regulates the pressure
differential between the annular space and the expansion chamber
during run-in of the expander tool. Further, a need exists for a
pressure regulation system for an expander tool which regulates
pressure during the expansion process, allowing the expander tool
to exert greater pressure during initial expansion to the
constraint point and lesser pressure to maintain expansion after
hitting the constraint point. Further still, there is a need for a
pressure regulation system for an expander tool which aids in
gradual transition within the expansion chamber of the expander
tool from the initial pressure to the pressure necessary to
maintain expansion.
SUMMARY OF THE INVENTION
[0013] The present invention provides an apparatus for expanding a
tubular body. More specifically, improved pressure regulation
systems for an expander tool are disclosed. In addition, the
present invention provides a method for expanding a tubular body,
such as a string of casing within a hydrocarbon wellbore, which
employs the improved pressure regulation systems of the present
invention.
[0014] The expansion system of the present invention comprises two
pressure regulation systems. Both pressure regulation systems may
be combined to produce a complete system for run-in and operation
of the expansion system, or, in the alternative, either of the
systems may be utilized in the expansion process separately.
[0015] The first pressure regulation system allows for pressure
regulation during run-in of the expansion system to equalize fluid
pressure between the annular space and the expansion chamber within
the expansion system, thus preventing collapse of the expansion
system. The first system comprises at least two valves which are
located internal to the expansion chamber of the expander tool. The
first valve allows pressure to exit from the expansion chamber into
the annular space, while the second valve allows pressure to exit
from the annular space into the expansion chamber.
[0016] The first pressure regulation system operates upon run-in of
the expansion system. After the expansion tool is run into the
depth at which the expansion process is to be performed, both
valves are isolated from the expansion process. Isolation occurs
when the valves are plugged, thus preventing fluid flow through the
two valves.
[0017] The second pressure regulation system is activated when
expander tool has been run into the desired depth for the tubular
expansion. The second system regulates pressure during the
expansion process. The expansion process occurs in two stages, each
stage requiring a different pressure within the expansion chamber.
In the first stage, an initial, high pressure is required to build
up enough fluid pressure within the expansion chamber to urge the
radially expandable members of the expander tool radially from the
body of the expander tool and into contact with the tubular
therearound, as well as to expand the tubular past its point of
elastic deformation and into the surrounding wellbore. In the
second stage, a lower pressure is necessary to maintain the
radially expandable members of the expansion tool in contact with
the tubular therearound while expanding the tubular into plastic
deformation along the predetermined length in the wellbore by
rotation and axial movement of the tubular within the wellbore.
[0018] Regulation of fluid pressure within the expansion chamber at
two predefined levels is accomplished by the second pressure
regulation system. In one embodiment, the second pressure
regulation system comprises a check valve and a frangible member in
fluid communication with the expansion chamber of the expansion
system. The check valve and the frangible member are placed in
series. The frangible member, which is preferably a burst plug,
permits the appropriate amount of fluid pressure to build up within
the expansion chamber to accomplish initial expansion of the
tubular by inhibiting flow through the plug until a designated
pressure is reached within the expansion chamber. When the pressure
necessary for initial expansion of the tubular is achieved and the
tubular reaches the constraint point, the frangible member bursts,
thus allowing a pressure drop sufficient to prevent excessive
thinning of the tubular wall. The check valve then begins to
regulate the pressure within the chamber of the expansion tool by
cycling from open to closed. The check valve permits a lesser
amount of fluid pressure to remain within the expansion chamber so
that the expansion process is completed without overexpanding the
tubular walls.
[0019] In another embodiment, the second pressure regulation system
may further comprise a pressure regulator downstream of the
frangible member and check valve in series. The pressure regulator
is preferably a jetted valve. The pressure regulator creates a back
pressure on the check valve, increasing the ability of the check
valve to cycle open to closed. The role of the pressure regulator
involves providing a smooth, efficient transition from the higher
pressure in the expansion chamber required for initial expansion of
the tubular to the lower pressure necessary to maintain
expansion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0021] FIGS. 1A-C depict a longitudinal cross-sectional view of a
closed expansion system which might be used with the present
invention, with the pressure regulation systems of the present
invention located in the closed expansion system. FIG. 1A is the
top portion of the expansion system, FIG. 1B is the middle portion
of the expansion system, and FIG. 1C is the bottom portion of the
expansion system. The expansion system is shown in the run-in
configuration.
[0022] FIGS. 2A-C show the expansion system of FIGS. 1A-C disposed
within a wellbore after being run into the wellbore, during the
initial expansion.
[0023] FIG. 3 is a longitudinal cross-sectional view of a portion
of the expansion system of FIG. 1 disposed within a wellbore at the
end of the expansion process.
[0024] FIG. 4 is an expanded cross-sectional view of one embodiment
of the second pressure regulation system of the present invention
shown in FIG. 1.
[0025] FIG. 5 is an expanded cross-sectional view of another
embodiment of the second pressure regulation system of the present
invention shown in FIG. 1.
[0026] FIG. 6 is an expanded cross-sectional view of the first
pressure regulation system of the present invention shown in FIG.
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0027] FIGS. 1A-C, 2A-C, and 3 are depictions of an expander tool
that is part of a closed expansion system which may utilize the
pressure regulation systems of the present invention. The pressure
regulation systems of the present invention are designed for use in
a closed expansion system, including but not limited to the closed
expansion system shown in FIGS. 1A-C, 2A-C, and 3.
[0028] FIGS. 1A-C show the expansion system in the run-in
configuration. An upper casing string 31 and a lower casing string
32 are disposed within a wellbore. In the run-in configuration, the
lower casing string 32, or liner, is lowered into the wellbore
co-axially with the upper casing string 31 by a casing working
string (not shown). The lower casing string 32 is ultimately
positioned such that an upper portion of the lower casing string 32
overlaps with a lower portion of the upper casing string 31. A
collett (not shown) may be used to support the lower casing string
32 on the casing working string.
[0029] The lower casing string 32 serves as an expandable tubular.
In particular, the lower casing string 32 will be hung in the upper
casing string 31 by expanding the upper portion of the lower casing
string 32 into the lower portion of the upper casing string 31, as
shown in FIG. 2B. However, it is understood that the apparatus and
method of the present invention may be utilized to expand downhole
tubulars other than strings of casing.
[0030] A sealing member (not shown) may be disposed on the outer
surface of the lower casing string 32 in order to seal an annular
area 33 between the lower outer surface of the lower casing string
32 and the inner surface of the upper casing string 31 as the upper
portion of the lower casing string 32 is expanded. Suitable sealing
members for preventing fluid flow through the annular space during
expansion are known by those skilled in the art. Also disposed on
the outer surface of the lower casing string 32 is at least one
slip member (not shown) to provide an improved grip between the
lower casing string 32 and the upper casing string 31 during
expansion of the lower casing string 32. Again, suitable slip
members for use in the expansion process are known to those skilled
in the art.
[0031] In order to expand the lower casing string 32 into the upper
string of casing 31 as seen in FIG. 3, an expander tool 2 is
provided. For clarity purposes, portions of the expander tool 2
which represent the pressure regulation systems of the present
invention have been enlarged in FIGS. 4, 5, and 6. Therefore, FIGS.
1A-C are described in conjunction with reference to FIGS. 4, 5, and
6, with like elements similarly labeled.
[0032] As shown in FIGS. 1A-C, the expander tool 2 includes a
rotatable mandrel 3 connected to an upper running tool (not shown)
with a torque anchor (not shown) thereon at an upper end and a
bottom connector 45 at a lower end. Torque screw threads (not
shown) may be used to connect the rotatable mandrel 3 to the upper
running tool so that the upper running tool may transfer torque to
the rotatable mandrel 3. The bottom connector 45 may be used to
connect other tools to the expander tool 2.
[0033] A lower spline assembly 49 is coupled to a lower portion of
the rotatable mandrel 3 using a first spline connection 52. The
lower spline assembly 49 includes a lower inner spline 50 at least
partially disposed in a lower outer spline 51. The lower inner
spline 50 shown in FIGS. 1A-B comprises four members 50A, 50B, 50C,
and 50D, and the members 50A, 50B, 50C, and 50D are connected by
pins. It is to be understood that the lower inner spline 50 may
comprise one or more members. The members 50A, 50B, 50C, and 50D of
the lower inner spline 50 translate together and house one or more
expandable members 15. Preferably, the lower inner spline 50 and
the lower outer spline 51 are tubular shaped and are coupled to
each other using a second spline connection 53. Specifically, the
second spline connection 53 consists of grooves formed on an inner
surface of the lower outer spline 51 which mate with splines formed
on an outer surface of the lower inner spline 50. The first spline
connection 52 coupling the lower spline assembly 49 to the
rotatable mandrel 3 includes splines formed on an inner surface of
a lower portion of the lower outer spline 51 which mates with
grooves formed on an outer surface of the rotatable mandrel 3. The
first and second spline connections 52 and 53 allow the rotatable
mandrel 3 to transfer torque to the lower inner spline 50 when the
mandrel 3 is rotated. The second spline connection 53 also allows
the lower inner spline 50 to extend and/or retract axially relative
to the lower outer spline 51.
[0034] The expander tool 2 contains an annular space formed between
the lower inner spline 50 and the rotatable mandrel 3. The annular
space acts as an expansion chamber 54 for containing hydraulic
fluid used to actuate one or more of the expandable members 15
disposed in the lower inner spline 50. Seals such as o-rings may be
used to prevent fluid leakage from the expansion chamber 54. As
shown in FIG. 6, lower seals 56 attached to the lower inner spline
50 are disposed between the rotatable mandrel 3 and the lower inner
spline 50. By attaching the lower seals 56 to the lower inner
spline 50, the lower seals 56 travel with the lower inner spline 50
during operation. To effectively retain the fluid, the lower seals
56 contact a mandrel taper 55 of pre-determined length formed on an
outer surface of the mandrel 3. The mandrel taper 55 allows the
lower seals 56 to seal in the fluid as they travel with the lower
inner spline 50. When the lower seals 56 move past the end of the
mandrel taper 55, the fluid is allowed to drain out of expansion
chamber 54. Fluid is introduced into the expansion chamber 54 prior
to lowering the expander tool 2 into the wellbore.
[0035] Pressure in the expansion chamber 54 is controlled during
run-in of the expansion system using a first pressure regulation
system 5, which is located within the expansion chamber 54 of the
expander tool 2, preferably located within the lower inner spline
50. The first pressure regulation system 5 comprises a first valve
57 on one side of the expansion chamber 54 and a second valve 58 on
the other side of the expansion chamber 54, the two valves 57 and
58 disposed in between the lower seals 56. Preferably, the first
pressure regulation system 5 is disposed below the expandable
members 15 of the expander tool 2. The first pressure regulation
system 5 is shown in FIG. 6. The first pressure regulation system 5
also comprises a fluid recess 90 between the rotatable mandrel 3
and the lower inner spline 50. As shown in the run-in configuration
in FIG. 1C, the first valve 57 allows fluid pressure to flow into
the annular space between the wellbore and the expander tool 2 from
the expansion chamber 54, while the second valve 58 allows fluid
pressure to flow from the expansion chamber 54 into the annular
space between the wellbore and the expander tool 2.
[0036] The lower inner spline 50 has a plurality of recesses 17 to
hold expandable members 15 capable of extending radially. The
expandable members 15 suitable for use in the present invention
include, but are not limited to, expander pads and expander
rollers. The expandable members 15 are supported on a piston 16 and
may be disposed within a cartridge 18 to facilitate replacement.
The cartridge 18 is then attached to the recess 17 in the lower
inner spline 50. The back of the piston 16 is exposed to the fluid
pressure in the expansion chamber 54. As the pressure is increased,
the fluid forces the pistons 16 from the recesses 17. This, in
turn, causes the expandable members 15 to contact the lower casing
string 32. Although two expandable members 15 are shown in FIG. 1B,
additional expandable members 15 may be added to the expander tool
2. Furthermore, only one recess 17/piston 16/cartridge
18/expandable members 15 assembly is depicted in FIG. 1B. Any
number of assemblies may be utilized in the present invention.
[0037] Also located inside the expansion chamber 54 is a second
pressure regulation system 70. The second pressure regulation
system 70 regulates fluid pressure inside the expansion chamber 54
during the expansion process, after the expander tool 2 is run into
the location at which the lower casing string 32 is to be expanded.
The second pressure regulation system 70, as seen in FIGS. 4 and 5
as well as FIG. 1B, is located in between the outer diameter of the
rotatable mandrel 3 and the inner diameter of the lower inner
spline 50. Reciprocal threads 76, 77 are located on the outer
diameter of the rotatable mandrel 3 and on the inner diameter of
the second pressure regulation system 70, respectively. Also, a
tubular member 80 is threadably connected to the lower inner spline
50. The reciprocal threads 76, 77 are disposed above and below a
frangible member 71 and a check valve 72 in series. The check valve
72 is disposed downstream of the frangible member 71 with respect
to fluid exiting the expansion chamber 54, so that the frangible
member 71 is closest to and is in fluid communication with the
expansion chamber 54. In the preferred embodiment shown in FIG. 5,
a pressure regulator valve 73 may be located downstream from the
check valve 72. The pressure regulator 73 is closest to and in
fluid communication with the annular space 75 outside the expansion
chamber 54. In another embodiment depicted in FIG. 4, the check
valve 72 is closest to and in fluid communication with the annular
space 75 outside the expansion chamber 54. In this embodiment, the
pressure regulator valve 73 is not utilized. In either embodiment,
upper seals 74 are located on the second pressure regulation system
70 to seal the annular space between the second pressure regulation
system 70 and the lower inner spline 50.
[0038] The frangible member 71 is any member which prevents fluid
from flowing through the frangible member 71 from the expansion
chamber 54 until a certain predetermined pressure is reached within
the expansion chamber 54. The frangible member 71 prevents fluid
flow from the expansion chamber 54 to the annular space 75 so that
enough pressure builds up within the expansion chamber 54 to
activate the expandable members 15 of the expander tool 2. When a
sufficient pressure to perform initial expansion of the lower
casing string 32 is reached within the expansion chamber 54, the
frangible member 71 breaks, placing the expansion chamber 54 in
fluid communication with the check valve 72. Preferably, a burst
plug is used as the frangible member 71. Burst plugs are known to
persons skilled in the art. The check valve 72 is a valve that
cycles from open to closed, allowing fluid to flow in one direction
while preventing fluid flow in the opposite direction. In the
present invention, the check valve 72 allows fluid to flow from the
expansion chamber 54 into the annular space 75 in the embodiment
shown in FIG. 4 and into the pressure regulator 73 in the
embodiment shown in FIG. 5. Check valves 72 useful in the present
invention are known to those skilled in the art. The pressure
regulator 73 is a valve comprising a smaller orifice than that
present in the check valve 72 to provide a tortuous path for the
fluid exiting the expansion chamber 54 and entering the annular
space 75, so that the transition is smooth from the higher pressure
in the expansion chamber 54 required for initial expansion of the
lower portion of the lower casing string 32 to the lower pressure
in the expansion chamber 54 required to maintain expansion up the
length of the lower casing string 32 (see FIG. 2B). The pressure
regulator 73 is preferably a jetted valve, which is known by those
skilled in the art.
[0039] Referring again to FIGS. 1A-C, the expander tool 2 further
includes an upper spline assembly 10 for axial translation of the
expandable members 15. Specifically, the upper spline assembly 10
includes an upper outer spline 60 coupled to an upper inner spline
61 using a third spline connection 59. Preferably, the upper outer
spline 60 and the upper inner spline 61 are tubular shaped. The
third spline connection 59 allows the upper inner spline 61 to
extend/retract axially relative to the upper outer spline 60. A
lower portion of the upper inner spline 61 is rotatably connected
to an upper portion of the lower inner spline 50 using a thrust
bearing assembly 62. The thrust bearing assembly 62 allows the
lower spline assembly 49 and the upper spline assembly 10 to rotate
independently of each other. Although a thrust bearing assembly 62
is used, other apparatus capable of allowing the spline assemblies
49 and 10 to rotate independently as known to a person of ordinary
skill in the art are also applicable.
[0040] A lower portion of the upper inner spline 61 has threads 63
that engage helical threads 64 formed on an outer surface of the
rotatable mandrel 3. A nut 66 having threads 63 is attached to the
upper inner spline 61 for engaging the rotatable mandrel 3. The
helical threads 64 are formed along a pre-determined length of the
outer surface of the rotatable mandrel 3. A connector 65 on the
upper portion of the upper outer spline 60 connects the upper
spline assembly 10 to the upper running tool (not shown) with the
torque anchor (not shown) thereon, thereby causing the upper spline
assembly 10 to be rotationally fixed within the wellbore. In this
manner, as the rotatable mandrel 3 is rotated, the threads 63 of
the upper inner spline 61 may ride along the helical threads 64 of
the rotatable mandrel 3 and axially advance the upper inner spline
61. Suitable torque anchors for use with the present invention are
well known in the art. The torque anchor moves axially, but not
rotationally, relative to the upper casing string 31.
[0041] FIGS. 1A, B, and C, FIGS. 2A, B, and C, and FIG. 3 show the
expansion system at various stages in the expansion process. In
operation, a torque anchor (not shown) is placed on a casing
working string (not shown) along with the expander tool 2 and the
lower casing string 32. The expander tool 2 is located at the lower
end of the casing working string, while the torque anchor is
located at the upper end of the casing working string. The casing
working string is temporarily connected to the lower casing string
32 to accomplish the expansion operation in a single trip. In this
manner, the lower string of casing 32 can be introduced into the
wellbore at the same time as the expander tool 2.
[0042] Prior to lowering the expander tool 2 into the wellbore, a
predetermined amount of hydraulic fluid is injected into the
expansion chamber 54 of the expansion tool 2. In the unactuated
position shown in FIGS. 1A-C, the pressure inside the expansion
chamber 54 is insufficient to actuate the expandable members 15.
During run-in of the expander tool 2, the expandable members 15
reside in the recesses 17.
[0043] The expander tool 2, lower casing string 32, and torque
anchor are lowered into the wellbore on the casing working string.
The expander tool 2 is lowered with the lower spline assembly 49 in
a retracted position and the upper spline assembly 10 in an
extended position. As the expander tool 2 is lowered into the
wellbore, the first pressure regulation system 5 operates to
equalize pressure between the expansion chamber 54 and the annular
space 47 between the expander tool 2 and the wellbore. In the open
position of the first pressure regulation system 5 shown in FIG.
1C, fluid flows from the annular space 47, through the first valve
57, into the fluid recess 90, and into the expansion chamber 54
when the pressure outside the expansion chamber 54 is higher than
the pressure inside the expansion chamber 54. Similarly, fluid
flows from the expansion chamber 54, into the fluid recess 90,
through the second valve 58, and into the annular space 47 when the
pressure within the expansion chamber 54 is higher than the
pressure outside the expansion chamber 54.
[0044] After the lower casing string 32 is lowered to the desired
depth within the wellbore, the torque anchor is activated so that
the torque anchor remains stationary during the rotation of the
rotatable mandrel 3. The torque anchor is rotationally fixed
relative to the upper casing string 31 when activated.
[0045] Actuation of the expander tool 15 begins with the rotation
of the casing working string. It is contemplated that rotation of
the rotatable mandrel 3 is accomplished by rotating the casing
working string from the surface. However, rotation may also be
achieved by activation of a downhole rotary motor, such as a mud
motor. Rotating the casing working string causes the rotatable
mandrel 3 to rotate. The first spline connection 52 transfers the
torque from the rotatable mandrel 3 to the lower spline assembly
49, thereby causing the expandable members 15 to rotate about the
inner surface of the lower casing string 32. Rotating the mandrel 3
also initiates the axial advancement of the expandable members 15.
As the rotatable mandrel 3 rotates, the threads 63 on the upper
inner spline 61 ride along the helical threads 64 of the rotatable
mandrel 3. Being rotationally fixed, the upper inner spline 61 is
advanced axially relative to the upper outer spline 60 and the
rotatable mandrel 3 as its threads 63 engage the threads 64 of the
rotatable mandrel 3. Connected to the upper inner spline 61, the
lower inner spline 50 and the expandable members 15 are pulled
along by the upper inner spline 61. Even though the lower inner
spline 50 is traveling axially, it must be noted that the lower
inner spline 50 continues to rotate with the rotatable mandrel 3
due to the thrust bearing assembly 62.
[0046] The axial advancement of the lower inner spline 50 causes
the first pressure regulation system 5 located thereon to travel
upward. FIG. 2C shows the first pressure regulation system 5 moved
upward relative to FIG. 1C upon activation of the expander tool 2.
When the expander tool 2 begins operating, the first pressure
regulation system 5 is isolated so that fluid no longer travels
between the annular space 47 and the expansion chamber 54.
Isolation occurs when the lower inner spline 50 advances axially
and the fluid recess 90 is no longer in fluid communication with a
recess 91 located on the inner diameter of the lower inner spline
50 adjacent to the first and second valves 57 and 58. In this way,
fluid pressure is permitted to build up within the expansion
chamber 54 to force the expandable members 15 to extend outward and
expand the lower casing string 32. FIG. 2C shows the first pressure
regulation system 5 in the isolated position, as fluid flow through
the recess 91 is blocked by the inner diameter of the rotatable
mandrel 3. Isolation of the first pressure regulation system 5
eliminates the first and second valves 57 and 58 as leak paths so
that pressure can build up within the expansion chamber 54.
[0047] As shown in FIG. 1B, the expandable members 15 reside in the
recesses 17 until the fluid pressure in the expansion chamber 54
rises above the initial pressure required for actuation of the
expandable members 15. Once the first pressure regulation system 5
is isolated, the continued axial advancement of the lower inner
spline 50 triggers an increase in hydraulic pressure in the
expansion chamber 54. Axial advancement of the lower inner spline
50 relative to the second pressure regulation system 70 compresses
the fluid in the expansion chamber 54, thereby causing a gradual
increase in hydraulic pressure in the expansion chamber 54. The
frangible member 71 blocks the relief of the pressurized fluid from
the expansion chamber 54 into the annular space 75. The pressure
increase behind the expandable members 15 provides the pressure
necessary for expansion. The pressure gradually extends the
expandable members 15 against the lower casing string 32, so that
the lower casing string 32 is expanded radially by the torque of
the casing working string. This stage in the expansion process is
shown in FIGS. 2A, 2B, and 2C.
[0048] The pressure continues to rise until it reaches the optimum
expansion pressure. The optimum expansion pressure is reached when
expansion of the lower casing string 32 is constrained by the upper
casing string 31, herein termed the constraint point. At the
constraint point, the length of the lower casing string 32 is
expanded against the upper casing string 31 as shown in FIG. 3.
Once the optimum expansion pressure is reached, the frangible
member 71 breaks and bleeds off fluid from the expansion chamber 54
to regulate the pressure in the expansion chamber 54. In the
embodiment shown in FIG. 5, fluid travels from the expansion
chamber 54, through the broken frangible member 71, through the
check valve 72, into the pressure regulator 73, and into the
annular space 75. Again, in the alternative embodiment shown in
FIG. 4, the fluid travels from the expansion chamber 54, through
the unobstructed frangible member 71, through the check valve 72,
and into the annular space 75.
[0049] In the preferred embodiment, the pressure regulator 73
increases the ability of the check valve 72 to cycle open to
closed, thus regulating pressure to a greater extent. Increased
regulation of pressure through the pressure regulator 73 provides a
smoother transition from the initial, higher pressure required for
initial expansion of the lower casing string 32 to the lower
pressure necessary to maintain the expansion of the remaining
length of the lower casing string 32. The pressure regulator 73
regulates the fluid volume allowed to travel through the check
valve 72 through jetting (choking) action of a tortuous path of
fluid. A small orifice within the pressure regulator 73 provides
the tortuous path for the fluid so that a sudden, large amount of
fluid pressure is not allowed to travel through the check valve 72
directly into the annular space 75. The pressure regulator 73
permits the check valve 72 to work more quickly to achieve a steady
state of reduced pressure and thereafter maintains the fluid
pressure at a steady rate. Placing the pressure regulator 73
downstream of the check valve 72 creates a back pressure on the
check valve 73, increasing the open/close response time of the
check valve 73 and producing increased pressure stability within
the expansion chamber 54 of the expander tool 2. Increasing
pressure stability and the open/close response time controls fluid
loss, produces a smoother transition from the higher, initial
pressure and the lower, maintained pressure, and maintains a more
stable, predefined pressure at the constraint point.
[0050] The second pressure regulation system 70 controls the
pressure exerted on the expansion members 15 and translated to the
lower casing string 32, thus preventing excessive wall thinning.
The second pressure regulation system 70 parameters may be easily
altered based upon the tensile strength and thickness of the
material of the tubular to be expanded.
[0051] FIG. 3 shows the expander tool 2 near the end of the
expansion process. At this point, the upper spline assembly 10 is
in a retracted position and the lower spline assembly 49 is in an
extended position. The lower inner spline 50 has moved the lower
seals 56 past the mandrel taper 55. Disengaged from the mandrel
taper 55, the lower seals 56 are no longer capable of retaining
fluid in the expansion chamber 54. The leakage of fluid relieves
the pressure in the expansion chamber 54, thereby deactivating the
expansion members 15. After the expansion members 15 have returned
to their respective recesses 17, the torque anchor is deactivated
and the collett is released from the lower casing string 32.
Thereafter, the expander tool 2 may be retrieved by pulling on the
casing working string.
[0052] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *